1. Field of the Invention
The present invention relates to a process for conveying articles supplied in respective flow lines adjacent to one another.
The invention has been developed with particular attention to the possible use in the field of plants for automatically packaging products, such as food products, for example confectionery products.
2. Description of the Relevant Art
Within the context of this application, the problem of sorting the flow of articles coming from respective source stations to subsequent processing stations located downstream in the direction of flow of the articles occurs relatively frequently. For example, the source stations can be packaging machines in which products such as snacks, biscuits, etc., packaged in flexible wrappers (flow-packs), are inserted in groups in respective boxes. The further processing stations can, for example, be wrapping machines in which each box is in turn inserted in a further wrapping in the form of a flexible wrapper of the flow-pack type.
Within the context of this application, a number of problems arise of which account must be taken.
Firstly, the source stations (for example, the boxing machines) usually supply a conveying line with parallel rows. Each source machine supplies a respective row with a flow of articles which, although it is substantially constant, is not completely continuous, owing to various reasons: for example, temporary stoppages of the source station because of a lack of packaging material, discharge of defective articles upstream or downstream of the source station, etc.
Secondly, the number of source stations and thus of the parallel rows of the flow of articles generated thereby is generally different from the number of processing stations provided downstream. For example, it is possible to envisage ten source stations (for example, ten boxing machines) downstream of which there are only two wrapping machines, or four wrapping machines of which two are intended to operate continuously whilst the other two are used to take account of possible interruptions in the operation of the other wrapping machines or of incidents occurring in the flow of articles to be packaged.
It is generally known to overcome the above problems by resorting to a so-called accumulation (or "store") function, that is, by providing for a certain amassing of articles (the so-called accumulation or store) between the outlets of the source stations and the inlets of the stations situated downstream, from which the articles themselves can be taken up in an ordered flow so as to be sent in a regular rhythm to the handling stations located downstream.
Although this situation is entirely satisfactory in theory, it conflicts with certain practical difficulties.
Firstly, forming an accumulation or store of articles generally requires the stoppage or at least a great deceleration of the movement of the advancing articles themselves. In modern packaging plants with high processing rates of the articles (some hundreds of units per minute), the speed of the advancing articles tends to be fairly high: any stoppage or great deceleration, above all when it occurs as a result of impact on the articles located downstream, may be particularly damaging, especially with fragile articles, with soft and yielding articles and/or with articles which, particularly when packaged, display marked resilience to knocks: in practice, one or more articles may well be bounced out of their box because of the effect of knocking against a stop barrier. Again, particularly when products which are not yet wrapped are used, the knocks can give rise to fragments or small pieces which can soil the packaging plant.
Secondly, the greater the linear speed of movement of the articles, the greater the space occupied by the accumulation or storage areas.